The instant invention relates to the delivery of an air and fuel mixture to the cylinders of an internal combustion engine. In particular, the invention relates to an electronic fuel injection system which compensates for the heat transferred from internal engine surfaces to the intake air prior to the air being confined in each cylinder. An Electronic Fuel Injection system includes a storage tank, an intake manifold, an exhaust manifold, tubing, a muffler, a fuel gauge, a fuel filter and an air cleaner. In addition, the system has a fuel pump. The basic control component of the fuel injection system is an electronic control unit. Various operating conditions are monitored, the information is continuously fed to the control unit, and the control unit correspondingly determines the amount of fuel being fed into the air-fuel mix.
Engine operating conditions are monitored by a variety of sensors and switches which transmit electrical data to the preprogrammed (or programmable) analog (or digital) computer that is the control unit. In prior art fuel injection systems, the sensors used included a manifold absolute pressure sensor that monitors changes in the intake manifold pressure and thereby signals the control unit regarding variations in engine speed and load, and barometric pressure and altitude.
Additional prior art monitoring devices generally include (1) temperature sensors (for coolant and intake air--and, in some cases, for crankcase oil in a four-stroke engine), each of which is mounted somewhere within the area to be monitored; (2) a throttle-position switch (or sensor) which monitors throttle movement and its position as a function of the vehicle speed; (3) a speed sensor, the duty of which is to synchronize fuel injection with cylinder-valve operations; and (4) (in some systems) a fast-idle valve that operates to by-pass additional air into the manifold for cold starting and may be supplemented by an air solenoid valve (which responds to engine coolant temperature).
The resultant fuel amount desired is achieved utilizing the electronic control unit to actuate the fuel injectors--one for each cylinder--as is well known.
It is an object of the instant invention to provide a fuel-air mixture which is optimum for the particular engine used.
It is also a further object of the invention to provide a sensor for sensing the temperature of the engine casing or internal engine surfaces and for providing such temperature data to the electronic control unit.
It is a further object of the invention to provide a temperature sensor for the internal engine surfaces for either a two-stroke or a four-stroke engine.